This invention relates to a tone information processing device for an electronic musical instrument of the type in which a digital signal obtained through conversion of an externally supplied acoustic or sound signal is stored in a memory to be used as a sound source signal for forming a tone signal.
Heretofore, various electronic musical instruments have been provided, in which an externally supplied sound signal representing a musical sound of a piano, violin, etc. or bird's chirping, etc. is stored in a memory after conversion to a digital signal based on a PCM system or the like and the stored signal is read out of the memory to be utilized as a sound source signal of a keyboard electronic musical instrument or the like. In such an electronic musical instrument, the external sound signal to be stored in the memory is digitized through sampling at a given frequency. Therefore, the stored waveform does not start at a zero crossing point and end at a zero crossing point. For this reason, a tone formed by reading out the stored signal from the memory may contain clicks or similar noise.
Further, there may be cases when external sounds having different pitches are stored together in a memory. In such a case, if these external sounds are written in and read out from the memory at a fixed sampling frequency and at a fixed address designation rate, the tone pitch varies with different external sounds, i.e., tones can not be played back at a correct pitch.
Further, in the prior art electronic musical instrument noted above, tones are formed by merely reading out the recorded external sounds. Therefore, the tones formed are rather poor in variations. In addition, the original sound of the tone formed can not be identified. At any rate, the status of playback obtained is rather monotonous.